Burden of COVID-19 Infection in Populations With High or Low Risk of Infection

SARS-CoV-2 infection currently affects more than two million people worldwide and has caused
the death of more than 150,000 people. In Lombardia there were 64.000 confirmed positive
subjects (64:10,000) and 12,000 dead, with a large number of healthcare workers (HCWs)
involved. However, the number of recovered is starting to rise and, thanks to the containment
measures introduced, the number of new cases per day is falling. However, the situation is
quite different in other part of Italy; f.i. in Molise, a southern Italy region, there is a
much lower incidence of positivity and mortality: 269 confirmed positive (9:10,000) and 16
deaths.

To plan the second phase of outbreak management, waiting for the development of a vaccine and
valid therapeutic tools, preventive interventions should be revisited based on evidence from
the literature and from local epidemiological data. However, although the infection is now
worldwide spread, some issues are still not known.

The actual number of subjects with an active or past SARS-CoV-2 infection is not known, since
the approach used was based on tests performed in severe cases and in their contacts, while
few investigations have been carried out on the general population. The impact of the
emergency on the health of both HCWs or general population is not yet known. Furthermore, the
reasons for the different spread of the infection in the North and South of the country, as
well as the different characteristics of the subjects who have or have had the infection with
respect to those who have not had it are not yet fully known; moreover, among the positive
ones, the characteristics associated with the development of the more serious forms or the
absence of symptoms, remain to be elucidated. In fact, the studies conducted so far were
large studies that collected few data or were more detailed studies focused only on few
hospitalized subjects.

It is therefore necessary to conduct new studies on the general population, based on large
samples randomly selected from populations at high and low spread of the infection as well as
in subgroups at higher risk such as HCWs, and based on a large set of collected data. The
aims of this project are: (i) to estimate the real prevalence of the SARS-CoV-2 infection and
seroconversion in two populations at high and low risk of infection, in a comparative way,
from the territories of ASST Sette Laghi of Varese, Lombardia region (confirmed cases
18:10,000) and a region at lower prevalence of confirmed cases such as the Molise region
(confirmed cases 9:10,000 subjects), also focusing on subgroups at higher risk such as
healthcare workers (HCWs); (ii) to estimate the rate of burnout and post-traumatic stress
disorder in HCWs during the study period; (iii) to identify factors associated with
SARS-CoV-2 infection positivity and follow up at mead-term its effect on health.

Finally, the investigators will biobank biological samples for future studies, in already
available specialized facilities.

(i) Cross sectional analysis in the general population Population. Residents in the
territories of ASST Sette Laghi and of Molise Region will be randomly selected from the
municipal registries, up to reach 3000 recruited subjects invited to participate according to
protocols used in previous study.

Data collection. All people who accept the invitation at the clinics (ASST Sette Laghi
Occupational Medicine in Varese, IRCCS Neuromed in Molise) will be asked to sign the informed
consent and a blood sample will be taken for testing of IgM and IgG against SARS-CoV-2 and
for storage in the biobank. Laboratory analyses will be performed to assess blood cell count,
CRP, glucose and insulin levels.

Serum IgM and IgG antibodies will be measured with the most suitable test available at the
moment of the recruitment.

To each subject an app and a website access will be given to complete questionnaires at the
time of recruitment and after 6 months.

Statistical analysis. The prevalence of positivity for IgM and IgG antibodies will be
calculated and the incidence during the outbreak period will be estimated. An analysis of the
differences between the two geographical areas will be performed.

(ii) Cross sectional analysis on HCWs Population. All HCWs from the occupational registries
of two Clinical Centers (ASST Ospedale di Circolo and IRCCS Neuromed) will be recruited.

Data collection. The HCWs who accept the invitation will be asked to sign the informed
consent and a blood sample drawn for the assay of SARS-CoV-2 IgM and IgG levels and for
storage in the biobank. Laboratory analyses will be performed to assess blood cell count,
CRP, glucose and insulin levels, cortisol level. To each subject an app and a website access
will be provided to complete questionnaires at the time of recruitment and after 6 months. In
particular, they will be asked to fill: (a) Maslach Burnout Inventory (MBI), for the
detection of the burnout level; (b) peritraumatic dissociative experiences questionnaire
(PTEQ) and Impact of Event Scale (IES), for the detection of symptoms attributable to PTSD;
(c) a reduced scale of the General Health Questionnaire (GHQ), to assess the level of
psychological distress. Clinical records for SARS-CoV-2 positive participants who were
hospitalized for COVID-19 will be collected in the hospital upon informed consent signature.

Statistical analysis. The prevalence of positivity to IgM and IgG antibodies will be analyzed
as described in paragraph (i). Furthermore, the prevalence and incidence of MBI and PTSD
disorders and the associations between the development of conditions and anamnestic, clinical
and laboratory factors will be analyzed through multivariable regression analyses.

(iii) Identification of factors associated with SARS-CoV-2 infection positivity and follow up
at mead-term its effect on health.

Development of a computerized application for data collection A dedicated website will be
developed to allow the administration, guided by telephone aid, of specific questionnaires.
Moreover, a smartphone app will be developed to follow-up participants for phase 2 COVID-19
triage and risk factors changes. Privacy and data safety will be implemented according to
Italian law and guaranteed by up to date encryption standards. Questionnaire will address
participants' general information (gender, age, biometrics, socio-economic status, current
and previous job), lifestyles (dietary habits, smoking status, physical activity), work or
leisure travel habits, previous and current diseases, pharmacological history (drugs,
vaccinations and supplements), as well as specific data about COVID-19 (if they are or have
been affected by the disease or they turned out to be positive to a screening). A follow up
questionnaire will evaluate evolution of COVID-19 (for affected people), together with
biometrics data, nutrition, physical activity, cardiovascular and neurological disorders,
cognitive ability, quality of life, modifications in socio-economic level, stress,
resilience.

Statistical analysis. The differences in the different variables collected between the sample
of the positive subjects and a number of controls paired by sex and age, taken from the
Objective 1 population will be calculated as well as the differences between the
asymptomatic/paucisymptomatic non-hospitalized positives and all the other positives
separated by severity (hospitalized, COVID). The analysis will be carried out through
multivariate logistic regression, considering any plausibly associated variables and checking
for bias from multiple tests.